Cockroaches have been around for over 300 million years. They’ve adapted through global changes, survived natural catastrophes, and even welcomed the human invasion of their natural habitats. While countless other species died off, roaches endured.
To survive, roaches can derive calories and trace nutrients from almost anything. Cockroaches will eat items that aren’t even technically food. Examples include paint, cigarette butts, glue, hair, paper, and even the corpses of other roaches. However, these insects prefer things like fruits, vegetables, and sugars. For cockroach species that primarily live outdoors, they feast on decaying tree bark, fermenting plants, and rotting carcasses.
Cockroaches can survive for a month without food. If completely deprived of water, they can survive for an entire week. However, this is rarely what kills off a cockroach. They are skilled at taking in water from humid environments and finding trace moisture anywhere they can. Food can even include the dead skin cells around your home or mildew in between bathroom tiles.
- 1 What Do Cockroaches Feed On?
- 2 What Foods Attract Cockroaches?
- 3 Do Cockroaches Like Sugar?
- 4 Are Cockroaches Omnivores?
- 5 How Do Cockroaches Eat Their Food?
- 6 How Often Do Cockroaches Need to Eat?
- 7 What Foods Do Cockroaches Hate?
What Do Cockroaches Feed On?
Like all living creatures, roaches need food to survive. However, most organisms have a limited range of food they can safely eat or digest. Roaches have no such qualms. Their nigh unbeatable digestive system ensures they can almost never get food poisoning.
Since they’re designed to eat rotting or decomposing matter, cockroaches quickly adapt to nearly any food source they discover. Their impressive metabolism ensures they can even get trace nutrients and calories from unlikely sources.
At the bare minimum, this helps them limp along during a food shortage without dying. Once better food is available, they’ll chow down and reenergize in case there’s another shortage. In a typical indoor environment, cockroaches will eat:
- Bread crumbs
- Certain cooking oils
- Coffee grinds
- Anything else that’s organic
When hungry and deprived of the above options, they will still survive off of things we don’t consider food. These include:
- Cigarette butts
- Nail clippings
- Dead skin
- Cockroach corpses
- Cockroach eggs
Why Can Roaches Eat Anything?
Roaches survive on unlikely food items because their digestion targets the base ingredients. For example:
- Soap and shampoo may contain vegetable oil or animal fat
- Paper has starch
- Leather has animal skin cells
Cockroaches are able to eat all of this because they have gut bacteria capable of digesting cellulose. The bacteria is a living organism on its own and uses the cockroach as a host. In return, it helps the roach digest any material it eats, even if it’s mildly toxic or difficult to break down on a molecular level.
In the wild, this helps roaches work as a natural recycling plant. When outdoors, cockroaches eat:
- Decaying tree bark
- Dead or injured bugs
- Rotting or fermenting plants
- Animal carcasses
Cockroaches are omnivorous scavenger insects. They do not hunt and kill their food. Instead, they feast on any food that is left over by predators or when things die naturally. Scavengers are opportunistic creatures that are capable of eating and digesting a wide variety of foods. That includes things that would normally make other animals ill.
What Foods Attract Cockroaches?
Of course, roaches still have preferences. They are mostly attracted to foods with a strong smell. Fruits, as an example, gain a more pungent smell the more they mature. This is especially desirable to cockroaches.
They respond to odors over short distances far better than long distances. This makes sense, as their instincts will drive them to the nearest available food source. It helps them avoid spending too much energy scavenging.
Even if they know an abundance of food is available far away, they will ignore it. Their sense of smell will draw them toward whatever they can find nearby. By saving additional energy, they can better endure food shortages in the future and retain all the calories they’ve gained.
This is also why roaches are seen as shy creatures. They will flee once lights are turned on and make their nests in hidden places near food. Just like when they’re scavenging, roaches like to play it safe and base their survival on the surest bet.
What Foods Do Roaches Prefer?
According to Chulalongkorn University, cockroaches heavily favor bananas over other kinds of foods. Researchers conducted an experiment using German cockroaches, the most common type of indoor roach in the world. The roaches were divided into two groups:
- Those which were starving (48 hours without food)
- Those which were full
The researchers then let them choose between:
- Cat food
It was discovered that male cockroaches preferred:
- Cat food
In that order. Female cockroaches preferred:
- Cat food
Researchers theorized that female roaches preferred protein-based foods. That’s because they needed more of it to gain the energy required for ootheca creation and incubation. That’s way more physiologically taxing than anything a male cockroach does.
Do Roaches Like Carbs?
In the above test, both male and female cockroaches preferred bananas and potatoes due to the carbohydrate content they provided. Carbohydrates are a great source of energy. They’re also a key chemical compound that aids in energy conservation and fat storage.
Knowing this, it’s safe to say that other carbohydrate-rich foods that weren’t used in the study are preferred by roaches. These include:
What Foods Do Roaches Prefer While Starving?
The foods that roaches preferred were also influenced by how hungry they were. The study showed that, after 48 hours without food, the cockroaches would eat whatever food was closest to them without any hesitation. When full, however, the cockroaches would take their time surveying each of the foods before they ate.
The texture is another important factor that cockroaches take into account. The researchers noticed that cockroaches were drawn to mushy foods that were easy to eat. The cat food they chose to use for the experiment was rigid.
It was theorized that, under stressful conditions such as starvation, the cockroaches are attracted to foods they can chew easily and quickly. This plays into the fact that roaches eat decaying and fermenting matter in the wild.
Since they munch on carcasses and rotting plants, it’s natural for roaches to want soft food. Although their mandibles are capable of eating thicker foods, the softer it is, the easier and faster this meal becomes.
Do Cockroaches Like Sugar?
Roaches have a peripheral gustatory system that sends signals to their brain, much like we do. Like us, when cockroaches eat sugar, their peripheral gustatory system stimulates their “sweet” receptors. They do actually like sugar because it’s sweet.
Roaches have no problem regularly consuming glucose. However, studies have shown that they are now adapting to avoid it. According to the journal Science, cockroaches have become averse to the glucose used in cockroach traps.
This isn’t to say that cockroaches now refuse to eat sugar. It does mean that the effectiveness of certain cockroach traps has been reduced.
The study proved that a bitter compound receptor is now stimulated alongside the sweet receptors. The study was published in 2013 and the topic has yet to be revisited. However, based on how adaptive roaches are, we can assume that their intolerance to glucose will only increase over the years.
Are Cockroaches Omnivores?
When people say that roaches eat everything, it’s not an exaggeration. Cockroaches are omnivores, meaning they eat both plant and animal matter.
Rotting tree bark and plants is their ideal choice. However, if they find a dead animal and nothing is competing for this food, they will happily eat the flesh.
Do Cockroaches Eat Humans?
What attracts cockroaches to animal matter is the keratin found within it. Keratin is a fibrous protein that our hair and nails are made of. The outer layer of our skin is also made of keratin, so cockroaches can bite humans.
However, they rarely get up close and personal with humans. They instead prefer to scavenge in our kitchens instead of our bedrooms. Only starvation or severe overcrowding would drive them to take a bite out of us.
Because of that, there are rare cases of roaches biting humans. They may crawl on you while you’re sleeping and try to nibble at your skin.
It’s rather disingenuous to say that roaches eat humans, though. The most they do is take a few bites and leave a mark that looks a lot like a mosquito bite. We are not a cockroach’s primary source of nutrition. If one had to choose between us and a piece of fruit, it would always choose the fruit.
How Do Cockroaches Eat Their Food?
Cockroaches are scavengers. Instead of hunting for and killing their food, they roam around until they are able to find something to eat.
They rely heavily on their sense of smell to uncover such food and prefer to eat whatever is nearby. When scavenging, they move their antennae from side to side in order to smell the food in the air. While it may be difficult to see, cockroaches do have mouths. This is made up of:
- A labrum
- A set of mandibles
- The maxillae
The labrum is a flap at the front part of the mouth and pulls the food toward their mouths. Since it works as a set of lips, the labium closes the chewing cavity to prevent food from falling out. Once the food is in, cockroaches use their mandibles to chew the food. Numerous creatures have mandibles that move up and down, but those of a cockroach move side to side.
Cockroaches do use their mandibles to tear big chunks of food into smaller chunks. However, it’s actually the maxillae that further break down the food to fully be ingested by the cockroach. The maxillae are basically the teeth of the cockroach, though they don’t look like regular ones. They are pincers located below the mandible that grind the food up into tiny, digestible pieces.
Cockroaches also have teeth in their stomach, called the gizzard, which is an organ composed of 6 plates. These are considered to be another set of teeth. Because of these multiple sets of teeth, roaches can chew up and digest tough objects like tree bark.
How Often Do Cockroaches Need to Eat?
Cockroaches spend nearly all their time scavenging for food and eating. They are active between 5 p.m. to 6 a.m. on average. Their peak hours are between 7-10 p.m. and then again between 4-5 a.m.
They hide away in their nests for the rest of the day until it’s scavenging time again. The energy they get from eating is quickly expended in the form of physiological functions, such as:
- Egg-laying, in the case of female roaches
Without food, cockroaches would be unable to do any of these crucial functions. According to the Journal of Insect Physiology, if young cockroaches go through a period of starvation before a molt, they will actually delay their molting cycle until food becomes available once more. The same thing happens with female cockroaches, who delay their reproduction cycle if they are starving.
How Long Can a Cockroach Live Without Food?
With the amount of time cockroaches spend eating, you’d think they would die the moment they no longer had food. Surprisingly, cockroaches can go a long time without it. They can last an entire month without food if they have enough water to drink.
Cockroaches can only last a week if completely deprived of water. They may survive for up to 3 weeks if they can get it from unlikely sources, such as humidity in the air.
Cockroaches are able to survive this long because they are cold-blooded insects. They cannot control their own body temperature and are affected by the temperature of their surroundings. That’s why outdoor cockroaches (like the American roach) have no problem living outside during summer and spring. However, they will move into human households to find shelter during the winter.
When it’s cold, there isn’t as much food around as usual. This ensures that cold-blooded insects need to conserve as much energy as possible. That’s given them a highly evolved internal energy-conserving system that allows them to go for long periods without any food.
What Foods Do Cockroaches Hate?
Despite the ingredients above, there are hardly any foods that roaches won’t eat. Unfortunately, human food is often a mixed bag of sugars and carbs that attract cockroaches, even if they contain the substances the roaches are averse to.
For example, cockroaches dislike baking soda. However, you can’t spread cake around your kitchen and hope it will repel cockroaches.
You can mix in oils and herbs from the list above to bait cockroaches into eating a toxic substance. However, there isn’t a single thing humans eat that cockroaches wouldn’t either.